(a) Authority To Execute Projects.—When the United States is designated as the Host Nation for purposes of executing a project under the North Atlantic Treaty Organization Security Investment Program (in this section referred to as the "Program"), the Secretary of Defense may accept such designation and carry out such project consistent with the requirements of this section.

(b) Project Funding.—The Secretary of Defense may fund authorized expenditures of projects accepted under subsection (a) with—

(1) contributions under subsection (c);

(2) appropriations of the Department of Defense for the Program when directed by the North Atlantic Treaty Organization to apply amounts of such appropriations as part of the share of contributions of the United States for the Program; or

(3) any combination of amounts described in paragraphs (1) and (2).

(c) Authority To Accept Contributions.—(1) The Secretary of Defense may accept contributions from the North Atlantic Treaty Organization and member nations of the North Atlantic Treaty Organization for the purpose of carrying out a project under subsection (a).

(2) Contributions accepted under paragraph (1) shall be placed in an account established for the purpose of carrying out the project for which the funds were provided and shall remain available until expended.

(3)

(A) If contributions are made under paragraph (1) as reimbursement for a project or portion of a project previously completed by the Department of Defense, such contributions shall be credited to—

(i) the appropriations used for the project or portion thereof, if such appropriations have not yet expired; or

(ii) the appropriations for the Program, if the appropriations described in clause (i) have expired.

(B) Funding credited under subparagraph (A) shall merge with and remain available for the same purposes and duration as the appropriations to which credited.

(d) Obligation Authority.—The construction agent of the Department of Defense designated by the Secretary of Defense to execute a project under subsection (a) may recognize the North Atlantic Treaty Organization project authorization amounts as budgetary resources to incur obligations against for the purposes of executing the project.

(e) Insufficient Contributions.—(1) In the event that the North Atlantic Treaty Organization does not agree to contribute funding for all costs necessary for the Department of Defense to carry out a project under subsection (a), including necessary personnel costs of the construction agent designated by the Department of Defense, contract claims, and any conjunctive funding requirements that exceed the project authorization or standards of the North Atlantic Treaty Organization, the Secretary of Defense, upon determination that completion of the project is in the national interest of the United States, may fund such costs, and undertake such conjunctively funded requirements not otherwise authorized by law, using any unobligated funds available among funds appropriated for the Program for military construction.

(2) The use of funds under paragraph (1) from appropriations for the Program may be in addition to or in place of any other funding sources otherwise available for the purposes for which those funds are used.

(f) Authorized Expenditures Defined.—In this section, the term "authorized expenditures" means project expenses for which the North Atlantic Treaty Organization has agreed to contribute funding.